1. Field of the Invention
The invention is related to electrically actuated fluid pumps and in particular to electromagnetic reciprocating fluid pumps.
2. Prior Art
Electromagnetic reciprocating fluid pumps have found wide acceptance for a variety of applications. In general these pumps are highly reliable, quite efficient and are capable of generating relatively high pressures for their size. Typical examples of such fluid pumps are disclosed in U.S. Pat. No. 2,994,792, "Reciprocating Electro-Magnetic Motor," issued to L. C. Parker in August 1961, U.S. Pat. No. 3,381,616, "Electromagnetic Fluid Pump", issued to H. P. Wertheimer, et al in May 1968; and U.S. Pat. No. 3,400,663 issued to H. P. Wertheimer on Sept. 10, 1968. All of these pumps embody a hollow magnetically permeable armature disposed in a guide cylinder and reciprocated against a resilient bias by an intermittently energized solenoid coil. The solenoid coil may be energized by the action of an internal electrical switch, as taught by Parker in U.S. Pat. No. 2,994,792, or by any other means known in the art. The present preference is to use a blocking oscillator as taught by Wertheimer in U.S. Pat. No. 3,381,616 or as taught by the applicant in U.S. Pat. No. 3,629,674 " Transient Resistant Transistorized Blocking Oscillator for Switching Inductive Loads", issued on Dec. 21, 1972. These pumps have the disadvantage in that their output pressure is determined by the diameter of the hollow armature and the force generated by the resilient (spring) member. Those skilled in the art will quickly recognize that to significantly increase the output pressure by decreasing the diameter of the armature, or increasing the force supplied by the resilient member would require a significant increase in the size and power requirements of the solenoid coil. The disclosed fluid pump overcomes this problem and further permits the use of an armature made from a ceramic magnetic material having comparatively higher electrical resistance. The higher electrical resistance reduces eddy current losses in the armature increasing the efficiency of the pumps, and permits the pump to be operated at higher frequencies.